As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Remote control or management of information handling systems has become an important aspect of network management. For example, Wake on LAN (WoL) technology has become an invaluable addition to networks of managed information handling systems, as it allows an administrator to power on an information handling system remotely, e.g., for system backups, installation of new software, or providing other maintenance.
WoL support is typically implemented in the motherboard of the information handling system. Most modern motherboards with an embedded Ethernet controller support WoL without the need for an external WoL cable. Older motherboards may require a WAKEUP-LINK header onboard and connected to the network card via a special 3-pin cable.
WoL must be enabled in the Power Management section of the motherboard's BIOS or operating system. It may also be necessary to configure the information handling system to reserve power for the network card when the system is shut down. In addition, in order to get WoL to work it is sometimes required to enable this feature on the card.
In general, waking up an information handling system in a LAN (e.g., a server blade) remotely can be explained as follows. The target blade is shut down, although power is still supplied to the blade's network card. The network card listens for a specific broadcast packet, called the “Magic Packet.” The blade receives the Magic Packet, checks it for the correct information, and then boots if the Magic Packet is valid.
The Magic Packet is a broadcast frame that can be sent over a variety of connectionless protocols (e.g. UDP or IPX), with UDP being the most commonly used. The data contained in a Magic Packet is the defined constant as represented in hexadecimal: FF FF FF FF FF FF followed by sixteen repetitions of the target computer's MAC address, sometimes followed by a four or six byte password.
WoL is fairly easy to implement at the network controller level, but has some inherent drawbacks. In particular, as mentioned above, WoL requires that the target computer's network card remains powered in order to listen for the Magic Packet or similar wake-up message. This may be especially undesirable in blade systems where the high density of compute resources and network controllers may place a fairly large power demand on the power subsystem even in cases where the blades are otherwise powered down. Historically, some blade implementers have avoided supporting WoL at least in part due to this power management issue. However, as MICROSOFT has made WoL support a requirement for Windows Hardware Quality Labs (WHQL) system certification, improved implementation of WoL—particularly in systems such as server blade systems—has become more important that ever.